<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>UI状态伪类选择器</title>
    <style>
        input:enabled{
            /* background: red; */
        }
        input:disabled{
            background: yellow;
        }
        
        /* 点击选中 会匹配该选择器 */
        input:focus{
            /* background: blue; */
        }

        input[type=checkbox]{
            /* 去掉默认样式 */
            appearance: none;
            width:20px;
            height: 20px;
            border: 1px solid black;}
        
        input:checked{
            background: red;
        }

        div::selection{
            background: yellow;
            color: red;
        }
    </style>
</head>
<body>
    <form action="">
        用户名：<input type="text"><br>
        密码：<input type="password"><br>

        记住用户名：<input type="checkbox"><br>
        <input type="submit" disabled>
    </form>

    <div>
        Lorem ipsum dolor sit amet consectetur adipisicing elit. Id error cumque enim dolorum optio aliquam minima iste laudantium, delectus sed nulla adipisci consequatur eos aspernatur! Iste cupiditate sequi optio recusandae?
    </div>
</body>
</html>